MTC (Machine-Type Communication) is an important revenue stream for operators and has a huge potential from the operator perspective. Based on the market and operators' requirements, there are two requirements for MTC operation in LTE (Long Term Evolution). One is low-cost of MTC UEs (User Equipments) and communication; another is improving the coverage of MTC UEs, for example 15 dB coverage enhancement is required for MTC enhancement. To enhance the MTC coverage, almost each of the physical channels need to be enhanced including (E)PDCCH ((Enhanced) Physical downlink Control Channel). For example, coverage enhancement target for (E)PDCCH is 9.6 dB for FDD (Frequency-Division Duplex) and 14.6 dB for TDD (Time-Division Duplex).
For (E)PDCCH, repetition in time domain is the main method to improve the coverage. Based on simulation results presented in 3GPP (The 3rd Generation Partnership Project) meeting, hundreds of repetitions are needed for (E)PDCCH transmission. For example, for (E)PDCCH with the coverage enhancement target 9.6 dB as described above, approximately 100˜200 repetitions are required. To satisfy multiple different coverage requirements, multiple repetition levels are supported and different repetition levels correspond to different integral (E)PDCCH repetition numbers. (E)PDCCH repetitions will be transmitted in multiple concentrated subframes. For each repetition level, integral (E)PDCCH repetitions transmit signals carrying one DCI (Downlink control information).